Microalloying of Ti–6Al–4V alloy by Fe addition has attracted interest as a promising way to improve castability and comprehensive mechanical performance.The mission of this work is twofold by employing the experime...Microalloying of Ti–6Al–4V alloy by Fe addition has attracted interest as a promising way to improve castability and comprehensive mechanical performance.The mission of this work is twofold by employing the experimental examination and the phenomenological analysis,(1)to investigate the effect of Fe addition on the microstructure features and mechanical properties of the Fe-containing Ti–6Al–4V(TC4-xF)alloys subjected to casting and homogenization treatment,and(2)to unveil the critical microstructure features in homogenization,hot-worked and aging treated alloys,respectively,that benefit the yield strength and the fracture toughness.Experimental observations evidence that the addition of 0.5 wt.%Fe is most effective in enhancing the tensile ductility and the modeⅠfracture toughness.Further Fe addition up to 0.7–0.9 wt.%results in plateau values of yield and ultimate strengths with some fluctuations.Phenomenological analyses screen out the microstructural strengthening and toughening determinants which exhibit distinct sensitivities on Fe content under different processing conditions.The solid solution strengthening is confirmed as the primary effect that governs the yield strength of the homogenization treated TC4-xF alloys,followed by the refined size of colony andαlamella,so does it for the hot-worked and the aging-treated alloys.The strengthening effect of Fe could be further promoted by hot-working but impaired by a prolonged annealing time or a lowered cooling rate.The type of crack propagation path and theαmorphology are discerned to play their own leading roles in different cases to influence the performance of fracture toughness.A long crack propagation distance that traverses broadα/βlamellae embraces a high crack propagation resistance and gives rise to enhanced fracture toughness.The experimental results enrich the dataset of microstructure features and mechanical properties of Ti–6Al–4V relevant alloys.While upon the phenomenological analysis,the discovered microstructural strengthening and toughening factors provide deeper mechanism insights into the mechanical behaviors of Fe-modified Ti-6Al-4V alloys and are of the technical importance to future machine-learning of microstructure-property relationship.展开更多
Computational thermodynamics,known as CALPHAD method when dawned in 1950s,aimed at coupling phase diagrams with thermochemistry by computational techniques.It eventually evolves toward kinetic simulations integrated w...Computational thermodynamics,known as CALPHAD method when dawned in 1950s,aimed at coupling phase diagrams with thermochemistry by computational techniques.It eventually evolves toward kinetic simulations integrated with thermodynamic calculations,i.e.,computational kinetics,including diffusion-controlled phase transformation,precipitation simulation,and phasefield simulation.In the meantime,thermodynamic,mobility,and physical property databases for multi-component and multi-phase materials,served as basic knowledge for materials design,are critically evaluated by CALPHAD approach combining key experiments,first-principles calculations,statistic methods,and empirical theories.The combination of these computational techniques with their conjugated databases makes it possible to simulate phase transformations and predict the microstructure evolution in real materials in a foreseeable future.Further links to microand macro-scale simulations lead to a multi-scale computational framework,and aid the search for the quantitativerelations among chemistry,process,microstructures,and materials properties in order to accelerate materials development and deployment.This is a new route of materials and process design pursued by Integrated Computational Materials Engineering(ICME)and Materials Genome Initiative(MGI).This article presents a review on the basic theories and applications,the state of the art and perspective of computational thermodynamics and kinetics.展开更多
Computational diffusion kinetics(CDK),with a spirit of and being coupled with the computational thermodynamics(CT,or called as the CALPHAD technique),plays increasingly important role in the alloy design/optimization ...Computational diffusion kinetics(CDK),with a spirit of and being coupled with the computational thermodynamics(CT,or called as the CALPHAD technique),plays increasingly important role in the alloy design/optimization and microstructure control during the processing of advanced metallic materials.This paper is to highlight recent progress of CDK in research with great focus on novel Ti and Zr alloys,which was largely performed in the authors’group.It ends with one representative example of the applications of CDK,coupled with CT,quantitative phase field,and three-dimensional(3D)statistical calculation,in designing the heattreatment schedule for the dual phase(αβ)Ti–6Al–4V alloys.展开更多
基金sponsored by the National Natural Science Foundation of China(Grant No.51801101)the Natural Science Foundation of Jiangsu Province(Grant No.BE2019119)
文摘Microalloying of Ti–6Al–4V alloy by Fe addition has attracted interest as a promising way to improve castability and comprehensive mechanical performance.The mission of this work is twofold by employing the experimental examination and the phenomenological analysis,(1)to investigate the effect of Fe addition on the microstructure features and mechanical properties of the Fe-containing Ti–6Al–4V(TC4-xF)alloys subjected to casting and homogenization treatment,and(2)to unveil the critical microstructure features in homogenization,hot-worked and aging treated alloys,respectively,that benefit the yield strength and the fracture toughness.Experimental observations evidence that the addition of 0.5 wt.%Fe is most effective in enhancing the tensile ductility and the modeⅠfracture toughness.Further Fe addition up to 0.7–0.9 wt.%results in plateau values of yield and ultimate strengths with some fluctuations.Phenomenological analyses screen out the microstructural strengthening and toughening determinants which exhibit distinct sensitivities on Fe content under different processing conditions.The solid solution strengthening is confirmed as the primary effect that governs the yield strength of the homogenization treated TC4-xF alloys,followed by the refined size of colony andαlamella,so does it for the hot-worked and the aging-treated alloys.The strengthening effect of Fe could be further promoted by hot-working but impaired by a prolonged annealing time or a lowered cooling rate.The type of crack propagation path and theαmorphology are discerned to play their own leading roles in different cases to influence the performance of fracture toughness.A long crack propagation distance that traverses broadα/βlamellae embraces a high crack propagation resistance and gives rise to enhanced fracture toughness.The experimental results enrich the dataset of microstructure features and mechanical properties of Ti–6Al–4V relevant alloys.While upon the phenomenological analysis,the discovered microstructural strengthening and toughening factors provide deeper mechanism insights into the mechanical behaviors of Fe-modified Ti-6Al-4V alloys and are of the technical importance to future machine-learning of microstructure-property relationship.
基金the financial supports from Oriental Scholarship and 085 Project launched by the Shanghai Municipal Education Commission
文摘Computational thermodynamics,known as CALPHAD method when dawned in 1950s,aimed at coupling phase diagrams with thermochemistry by computational techniques.It eventually evolves toward kinetic simulations integrated with thermodynamic calculations,i.e.,computational kinetics,including diffusion-controlled phase transformation,precipitation simulation,and phasefield simulation.In the meantime,thermodynamic,mobility,and physical property databases for multi-component and multi-phase materials,served as basic knowledge for materials design,are critically evaluated by CALPHAD approach combining key experiments,first-principles calculations,statistic methods,and empirical theories.The combination of these computational techniques with their conjugated databases makes it possible to simulate phase transformations and predict the microstructure evolution in real materials in a foreseeable future.Further links to microand macro-scale simulations lead to a multi-scale computational framework,and aid the search for the quantitativerelations among chemistry,process,microstructures,and materials properties in order to accelerate materials development and deployment.This is a new route of materials and process design pursued by Integrated Computational Materials Engineering(ICME)and Materials Genome Initiative(MGI).This article presents a review on the basic theories and applications,the state of the art and perspective of computational thermodynamics and kinetics.
基金supported by the State Key Laboratory of Solidification and Casting, Northwestern Polytechnical University (SKLSP200906)the Program of Introducing Talents of Discipline to Universities (B08040)Yuwen Cui would like to acknowledge the support under the AMAROUT-II Program
文摘Computational diffusion kinetics(CDK),with a spirit of and being coupled with the computational thermodynamics(CT,or called as the CALPHAD technique),plays increasingly important role in the alloy design/optimization and microstructure control during the processing of advanced metallic materials.This paper is to highlight recent progress of CDK in research with great focus on novel Ti and Zr alloys,which was largely performed in the authors’group.It ends with one representative example of the applications of CDK,coupled with CT,quantitative phase field,and three-dimensional(3D)statistical calculation,in designing the heattreatment schedule for the dual phase(αβ)Ti–6Al–4V alloys.
